An industrial robot having articulated horizontal arms usually comprises a vertical post fixed to a floor, a first arm rotatably attached to the post, a second arm rotatably attached to the first arm, and a wrist portion attached to an end of the second arm, which wrist portion rotatable and can move linearly. Of course, other industrial robots having articulated horizontal arms exist, such as a robot which comprises an inner trunk body movable upward and downward on the base of the vertical post, the first arm being rotatably attached to the inner trunk body, but an indirect drive motor driving through a transmission mechanism may be adopted as a drive motor for the first arm or the second arm in such an industrial robot having articulated horizontal arms. When a direct drive motor is adopted, a robot does not necessarily have a compact structure, since it must be equipped with a brake unit and a rotation position detector.